Tumoral calcinosis of the knee treated with open, physeal sparing iliotibial band ACL reconstruction

Tumoral calcinosis is a hereditary disease of calcium and phosphate metabolism causing peri-articular tumors of calcium deposits. We present a case of tumoral calcinosis in a 13-year-old male with a history of a 12q13.11 genetic deletion. Surgical resection of the tumor necessitated resection of the ACL in its entirety with curettage and adjuvant therapy to the lateral femoral notch, which resulted in ligamentous instability and bony structural incompetency at the femoral insertion. Given the patient's radiographically-apparent skeletal immaturity, and lack of reliable bony architecture to accommodate a femoral ACL tunnel, ACL reconstruction was performed using a physeal-sparing technique. This is a case of tumoral calcinosis treated with, to our knowledge, the first ACL reconstruction using this modified open technique.

The Value of Signaling an Orthopaedic Surgery Program: A Survey to Orthopaedic Surgery Programs

INTRODUCTION

A new system was implemented by the Association of American Medical Colleges called the preference signaling program for the 2022 to 2023 orthopaedic surgery residency match. Applicants were able to signal 30 orthopaedic surgery programs to indicate high interest in a specific program. The purpose of this study was to address how important signaling was to an orthopaedic surgery program this 2022 to 2023 application cycle.

METHODS

A five-question survey was sent to orthopaedic surgery residency programs participating in the Electronic Residency Application Service this application cycle. Contact information was gathered through the Accreditation Council for Graduate Medical Education residency website and program websites.

RESULTS

Responses were obtained from 69 of the 151 programs (46%) contacted. The average number of applicants per program was 727 (range, 372 to 1031, SD 155). Thirty-four of 61 respondents (56%) stated that 100% of their interviewees signaled their program. Fifty-five of 61 respondents (90%) indicated that their interviewee pool consisted of 75% or more applicants who signaled. Applicants who signaled had a 24.4% (range, 12.77 to 47.41, SD 8.04) chance of receiving an interview. Applicants who did not signal had just a 0.92% (range, 0 to 13.10, SD 2.08) chance of receiving an interview. Fifty-four of the 63 applicants (86%) answered that signaling played an important role in considering an applicant for an interview.

CONCLUSION

Over half of the responding programs only interviewed applicants who signaled their program, and over 90% of programs' interview lists consisted of at least 75% of signaling applicants. Eighty-six percent of programs indicated that signaling played an important role in considering an applicant for an interview. Applicants who signaled were 26.5 times more likely to receive an interview than those who did not (P < 0.0001). With this information, applicants can narrow down their list of programs to apply to, knowing that their signal to a program will give them a better chance at receiving an interview.

Fine mapping and cloning of the major seed protein quantitative trait loci on soybean chromosome 20

Soybean is the most important source of protein meal worldwide and the quantitative trait loci (QTL) cqSeed protein‐003 on chromosome 20 exerts the greatest additive effect of any protein QTL mapped in the crop. Through genetic mapping and candidate gene downregulation, we identified that an insertion/deletion variant in Glyma.20G85100 is the likely gene that underlies this important QTL.

Intraoperative navigation and preoperative templating software are associated with increased glenoid baseplate screw length and use of augmented baseplates in reverse total shoulder arthroplasty

Background

Preoperative templating software and intraoperative navigation have the potential to impact baseplate augmentation utilization and increase screw length for baseplate fixation in reverse total shoulder arthroplasty (rTSA). We aimed to assess their impact on the (1) baseplate screw length, (2) number of screws used, and (3) frequency of augmented baseplate use in navigated rTSA.

Methods

We compared 51 patients who underwent navigated rTSA with 63 controls who underwent conventional rTSA at a single institution. Primary outcomes included the screw length, composite screw length, number of screws used, percentage of patients in whom 2 screws in total were used, and use of augmented baseplates.

Results

Navigation resulted in the use of significantly longer individual screws (36.7 mm vs. 30 mm, P < .0001), greater composite screw length (84 mm vs. 76 mm, P = .048), and fewer screws (2.5 ± 0.7 vs. 2.8 ± 1, P = .047), as well as an increased frequency of using 2 screws in total (35 of 51 patients [68.6%] vs. 32 of 63 controls [50.8%], P = .047). Preoperative templating resulted in more frequent augmented baseplate utilization (76.5% vs. 19.1%, P < .0001).

Conclusion

The difference in the screw length, number of screws used, and augmented baseplate use demonstrates the evolving role that computer navigation and preoperative templating play in surgical planning and the intraoperative technique for rTSA.

Adolescent vertebral osteomyelitis mimicking a neoplasm

A 14-year-old previously healthy girl presented with atraumatic onset of low back and flank pain and mildly elevated inflammatory markers. Magnetic resonance imaging disclosed an L5 superior endplate fracture, and cultures grew methicillin-susceptible Staphylococcus aureus. We discuss the variable presentations and appropriate treatments of adolescent vertebral osteomyelitis.

Primary bone sarcoma with BCOR internal tandem duplication

BCOR internal tandem duplications (ITDs) and rearrangements are implicated in the oncogenesis of a subset of undifferentiated sarcomas. To date, BCOR ITD sarcomas have been exclusively found in non-appendicular infantile soft tissues, whereas BCOR-rearranged sarcomas occur in both bones and soft tissues affecting a wider patient age range. Little is known about patient outcome in BCOR ITD sarcomas. We present a BCOR-expressing, primary bone, undifferentiated sarcoma case involving an adolescent male's left tibia that, unexpectedly, harbored a BCOR ITD instead of a BCOR rearrangement. Furthermore, the patient achieved a partial histologic response after receiving a Ewing sarcoma chemotherapy regimen. Our case expands the clinical spectrum of BCOR ITD sarcomas and suggests that childhood and adult BCOR-expressing sarcomas with an undifferentiated histology should be considered for both BCOR rearrangement and ITD screening. Accurate BCOR mutation identification in undifferentiated sarcomas is essential to define their clinical spectrum and to develop effective management strategies.

Fibrous Dysplasia in the Calcaneus

Fibrous dysplasia in the calcaneus is extremely rare; the most common locations of monostotic fibrous dysplasia of extremity bones being the proximal femoral shaft, tibia, humerus, and radius. An extensive literature search has revealed only 3 case reports that have been published concerning this topic, the most recent published in 2003. This is a case report of fibrous dysplasia in the calcaneus of a young male, including a discussion of the classical presentation of fibrous dysplasia and how this case differed.

LEVELS OF EVIDENCE

Therapeutic, Level IV: Case study.

Nestleaving and Coresidence by Young Adult Children

Using data from the National Survey of Families and Households on focal children in 1987-1988 aged 18 years and older and out of high school in 1992-1993, the authors investigated associations between parent-child coresidence in early adulthood and parents' reports of the quality of parent-child and marital relations. The quality of parent-child or marital relations at Wave 1 had little relation to whether children coresided at Wave 2; child situations were the primary predictors. Children who left and returned tended to be negatively selected on prior relationship quality, but parents accommodated them nonetheless. Coresidence between waves did not affect marital quality or general parent-child relations at Wave 2, though it was associated with increased parent-child disagreements, particularly when prior disagreement was greater. Coresidence appeared to be experienced as part of ongoing exchanges between parents and adult children.

Close To You? How Parent-Adult Child Contact Is Influenced by Family Patterns

OBJECTIVES

Intergenerational contacts occur in the context of other family relationships. We examine how in-person contacts among parents and all adult children affect each other, focusing on proximity and other predictors to assess whether and how visiting is correlated across adult children.

METHODS

We use a modeling approach derived from an adaptation of multilevel models to provide a convenient mechanism by which to write child-specific equations, each with its own set of predictors, and wherein one child's attribute values can be attached to other children's records.

RESULTS

We find that parent-adult child visiting is positively correlated across siblings, but the frequency of visiting within families is not directly reciprocated. Rather, visiting responds to common family factors. Visiting declines with distance, but there are strong discontinuities in the effect. Distance between parents and a focal child is positively associated with visiting with other children.

DISCUSSION

The empirical patterns we report can be framed within enhancement and compensation models. Positive correlations and cross-sibling interactions that juxtapose levels of visiting against not seeing a child in last 12 months are consistent with the enhancement model. The cross-sibling interaction for distance, whereby one child's farther distance leads to more visits reported with others, provides evidence of a countervailing, though, weaker, pattern of compensation for proximity.

Change in perceived age in middle and later life

Analyses examine change in the age people "feel" (felt age) and "would like to be" (ideal age) (relative to current age) in middle and later life. Data are from 1,815 respondents in two waves (1995-96, 2004-06) of the Midlife in the United States Survey (MIDUS) who were age 40+ at Wave 1. In aggregate, people feel about the same amount younger but become increasingly distant from preferred age. Favorable health trends between waves and better expected future health are related to younger felt age, cross-sectionally and longitudinally. Health is not related to ideal age, but education and (for respondents younger than 60) better financial expectations are associated with less youthful ideal age. Patterns for felt age appear to reflect images of later life as a time of physical decline, whereas ideal age appears to be shaped more by socioeconomic considerations.

Intraoperative navigation for minimally invasive resection of periarticular and pelvic tumors

The surgical approach to benign, metastatic, and some low-grade malignant tumors is often difficult due to their typically precarious locations. This article presents a series of cases where intraoperative stealth navigation was used to treat periarticular tumors. The use of paired point imaging with image fusion has made approaching tumors through an accurate and minimally invasive technique a viable option for the treatment of a subset of musculoskeletal tumors.

How old am I? Perceived age in middle and later life

Literatures on perceived age and developmental issues in middle and later life are joined in analyzing perceived age and its implications for well-being. Respondents aged 40-74 (N = 2,696) are drawn from the national MIDUS survey, containing developmental variables such as personal growth and insight into past. People generally "feel" (felt age) and would "like" (ideal age) to be younger, but these exhibit different predictors and outcomes. Younger felt age is associated with positive developmental assessments and enhanced well-being, whereas younger ideal age is associated with less positive assessments and lower well-being. The association between felt age and well-being is moderated by developmental assessments. The contrasting patterns exhibited by felt age and ideal age reflect the complexities of age perceptions. It is suggested that felt age entails perceptions of current circumstances as they relate to expectations about aging, whereas ideal age reflects a comparative overview of the life cycle.

Multiple parent-adult child relations and well-being in middle and later life

OBJECTIVES

Despite the centrality of parent-adult child relations, prior research has found only weak associations with parent well-being. There is a need to give more explicit attention to the relations of parents with multiple children and to the potentially mixed or "ambivalent" nature of those relations. These patterns may differ for mothers and fathers.

METHODS

Wave 1 of the National Survey of Families and Households provided detailed information on relations between parents and each of their adult children. The sample included 2,270 persons aged 50+ who had at least one child aged 19+.

RESULTS

Measures across multiple adult children uncovered more mixed patterns of "collective ambivalence" that included lesser quality and/or contact with at least some children. The presence of less positive relations with any children was consistently, albeit modestly, related to lower parent well-being. Mothers reported higher "maximum" quality and interaction across children, but mothers and father did not differ in "minimum" reports. Associations between parent-child relations and well-being were similar for mothers and fathers.

DISCUSSION

Analyses that incorporate the relations of parents with their multiple adult children, viewed as part of a family network, yield a more comprehensive and nuanced view of those relations and their implications for well-being.

Resistance to intercompartmental mass transfer limits β2-microglobulin removal by post-dilution hemodiafiltration

Although clearance of beta(2)-microglobulin is greater with hemodiafiltration than with high-flux hemodialysis, beta(2)-microglobulin concentrations after long-term hemodiafiltration are only slightly less than those obtained with high-flux hemodialysis. Resistance to beta(2)-microglobulin transfer between body compartments could explain this observation. beta(2)-Microglobulin kinetics were determined in patients receiving on-line post-dilution hemodiafiltration for 4 h with 18 l of filtration. Plasma beta(2)-microglobulin concentrations were measured during and for 2 h following hemodiafiltration and immediately before the next treatment. The filter clearance of beta(2)-microglobulin was determined from arterial and venous concentrations. The beta(2)-microglobulin generation rate was calculated from the change in the plasma concentration between treatments. The intercompartmental clearance was obtained by fitting the observed concentrations to a two-compartment, variable volume model. The plasma clearance of beta(2)-microglobulin by the filter was 73 +/- 2 ml/min. Plasma beta(2)-microglobulin concentrations decreased by 68 +/- 2% from pre- to post-treatment (27.1 +/- 2.2-8.5 +/- 0.7 mg/l), but rebounded by 32+/-3% over the next 90 min. The generation rate of beta(2)-microglobulin was 0.136 +/- 0.008 mg/min. The model fit yielded an intercompartmental clearance of 82 +/- 7 ml/min and a volume of distribution of 10.2 +/- 0.6 l, corresponding to 14.3 +/- 0.7% of body weight. Hemodiafiltration provides a beta(2)-microglobulin clearance of similar magnitude to the intercompartmental clearance within the body. As a result, intercompartmental mass transfer limits beta(2)-microglobulin removal by hemodiafiltration. This finding suggests that alternative strategies, such as increased treatment times or frequency of treatment, are needed to further reduce plasma beta(2)-microglobulin concentrations.

Marital Implications of Parent-Adult Child Coresidence: A Longitudinal View

OBJECTIVES

This study assesses implications of changes in coresidence with adult children for parents' marital relations, hypothesizing that transitions into coresidence lower marital quality and transitions out of coresidence increase marital quality.

METHODS

Panel data from Waves 1 and 2 of the National Survey of Families and Households are used to analyze whether change in three measures of marital quality-time together, happiness, and disagreements-is related to adult child coresidence.

RESULTS

When adult children move out, parent couples increase their time together; there is a tendency for reduced time together when the nest "refills." However, there are no effects of moves in or out on the marital happiness of parents or the number of marital disagreements they have. There is also no effect on time together or on marital quality when one adult child moves out but another moves in during the same period. The presence of younger children has more consistent associations with marital quality.

DISCUSSION

Coresidence with adult children does not appear to be an experience that disrupts the quality of marital relations. It may be that qualitative dimensions of coresidence experiences with adult children matter more than coresidence per se.

Increasing dialysate flow rate increases dialyzer urea mass transfer-area coefficients during clinical use

Dialyzer clearance depends on blood and dialysate flow rates and the product of the membrane surface area and mass transfer coefficient for the solute of interest, K(o)A. K(o)A is usually assumed to be constant for a given dialyzer and solute. Results of two recent studies challenge this assumption. Therefore, we examined the hypothesis that K(o)A depends on blood and dialysate flow rates during clinical dialysis. Urea clearances were measured for two different dialyzers at all four combinations of two blood flow rates (300 and 400 mL/min) and two dialysate flow rates (500 and 800 mL/min). Urea K(o)A was calculated by using standard equations for mass transfer in dialyzers operated with countercurrent flows. The impact of blood and dialysate flow rates on K(o)A was assessed by analysis of variance. Increasing dialysate flow rate from 500 to 800 mL/min significantly increased K(o)A (P = 0.018). Increasing blood flow rate from 300 to 400 mL/min did not significantly increase K(o)A (P = 0.083). Also, K(o)A decreased significantly with increasing hematocrit (P = 0.022). The results of this study extend previous in vitro findings by showing that increasing the dialysate flow rate increases urea K(o)A during clinical dialysis. However, the increase in K(o)A observed during clinical dialysis (5.7%) is less than that previously reported in vitro (14.7%), possibly because of the impact of blood cells and proteins on blood-side mass transfer resistance.

Priming of the neutrophil respiratory burst involves p38 mitogen-activated protein kinase-dependent exocytosis of flavocytochrome b558-containing granules

The respiratory burst of human neutrophils is primed by a number of pro-inflammatory stimuli, including tumor necrosis factor-alpha (TNFalpha) and lipopolysaccharide (LPS); however, the mechanism of priming remains unknown. LPS has been shown previously to increase membrane expression of flavocytochrome b(558), a component of the NADPH oxidase. This study shows that TNFalpha also increases membrane expression of flavocytochrome b(558). Mitogen-activated protein kinase (MAPK) modules have been implicated in the action of priming agents. Pharmacologic inhibitors of MAPKs, SB203580 and PD098059, revealed that priming of the respiratory burst and up-regulation of flavocytochrome b(558) are dependent on p38 MAPK but not on extracellular-signal regulated kinase (ERK). TNFalpha and LPS primed respiratory burst activity and increased membrane expression of CD35 and CD66b, specific markers of secretory vesicles and specific granules that contain flavocytochrome b(558), with similar time courses and concentration dependences. These processes also required p38 MAPK but were independent of ERK. TNFalpha failed to prime respiratory burst activity or to increase membrane CD35 expression in enucleated neutrophil cytoplasts. These data suggest that one mechanism by which TNFalpha and LPS prime neutrophil respiratory burst activity is by increasing membrane expression of flavocytochrome b(558) through exocytosis of intracellular granules in a process regulated by p38 MAPK.

Ultrapure dialysate: a desirable and achievable goal for routine hemodialysis

United States standards for the microbiologic quality of dialysate are not very stringent and have remained unchanged for more than 20 years, despite significant changes in the patient population and in the technology of hemodialysis. Numerous studies have demonstrated that bacterial products can cross dialysis membranes and stimulate an inflammatory response in the patient. Inflammation has been implicated in several complications associated with long-term hemodialysis therapy, and the use of ultrapure dialysate has been shown to reduce the incidence of one of these complications, beta2-microglobulin amyloidosis. Since technological innovations in water treatment and improvements in dialysis machine design allow the routine production of ultrapure dialysate, its use should now become standard.

Deficient homologous desensitization of formyl peptide receptors stably expressed in undifferentiated HL-60 cells

The ability of formyl peptide receptors (FPRs) stably expressed in undifferentiated HL-60 cells to undergo ligand-induced desensitization was compared with their ability in normal and vector-transfected HL-60 cells following granulocyte differentiation with DMSO. fMet-Leu-Phe failed to induce uncoupling of FPRs from G-proteins in FPR-transfected cells, whereas uncoupling was induced in differentiated HL-60 cells and differentiated vector-transfected HL-60 cells, as determined by ligand-stimulated guanosine 5'-(gamma-thio)triphosphate (GTPgammaS) binding and GTPgammaS inhibition of fMet-Leu-Phe binding to isolated membranes. Immunoprecipitation of Galpha(i2) from solubilized, azidoanalide (AA-gammaGTP) photolabeled membranes showed that receptors in desensitized FPR-transfected HL-60 cells remained coupled to Galpha(i2), whereas desensitized receptors in differentiated HL-60 cell membranes were uncoupled from Galpha(i2). As determined by immunoblotting, Galpha(i2) expression was similar in undifferentiated and differentiated HL-60 cells and FPR-transfected cells. Ligand-stimulated receptor internalization and desensitization of calcium redistribution were similar in all three groups of cells. Immunoblotting also indicated that G-protein-coupled receptor kinases (GRKs) 2 and 4 were present in undifferentiated FPR-transfected HL-60 cells at 50% of the level seen in differentiated HL-60 cells. However, differentiation did not increase GRK2 or GRK4 expression, indicating that differences in GRK expression do not explain deficient desensitization. The data indicated that undifferentiated HL-60 cells are unable to induce homologous desensitization of FPRs.

Summary of new distribution records for mosquito species in the United States and Canada for the period 1981-99

In order to elucidate the recent spread of mosquito species in the United States and Canada, a summary of new records for states and provinces has been prepared to include those reported mostly from 1981 to 1998, although some records before 1989 are also given. We are reporting 132 new records for 58 species of mosquitoes.

Improved dialyzer reuse after use of a population pharmacodynamic model to determine heparin doses

Anticoagulation with heparin is performed to prevent clotting during dialysis. However, heparin doses are usually determined empirically, and dialyzer clotting is a common reason for discarding reused dialyzers. We hypothesized that using a population pharmacodynamic model to determine individual heparin doses would improve dialyzer reuse rates. A previously published model was used to determine the loading dose and infusion rate of heparin needed to increase the intradialytic whole-blood clotting time to 150% of the predialysis value. The effectiveness of the model was assessed by comparing dialyzer reuse rates and delivered Kt/V(urea) before and after implementation of the model in 22 chronic hemodialysis patients. As an additional control, a similar group of 22 patients were followed up during the same period without adjustment of their heparin doses. Implementation of the model resulted in no change in the average loading dose (2,382 +/- 628 versus 2,425 +/- 908 IU; P = not significant) or average infusion rate (1,398 +/- 367 versus 1,393 +/- 532 IU/h; P = not significant) of heparin. However, individual patients required changes in loading dose or infusion rate. Dialyzer reuse rates increased significantly over time in the treatment group but remained unchanged in the control group (P < 0.003). Kt/V(urea) remained unchanged throughout the study period in both patient groups. From these data, we conclude that the use of a heparin model can improve dialyzer reuse rates without compromising the delivered dose of dialysis.

Cruciate injury patterns in knee hyperextension: a cadaveric model

We created an experimental model to evaluate the effects of strain rate on the mechanism of combined cruciate ligament injuries in knee hyperextension. Using straight knee hyperextension to rupture the anterior and posterior cruciates, two strain rates (approximately 100% per second and 5400% per second) were applied to reproduce two clinical injury patterns of the knee: low energy (sporting) and high energy (pedestrian-motor vehicle accident). Ten pairs of fresh-frozen cadaveric knees were injured to 45 degrees of hyperextension. Strain rate sensitivity of the posterior cruciate ligament was shown in this model, with midsubstance tears occuring in specimens tested at a low rate and avulsion "stripping" injuries from the femoral side occuring at a high rate. A variable pattern of anterior cruciate ligament tears at both high and low rates suggests that the specific injury mechanism may also involve other factors including notch morphology. We present a simplified mathematic model used to estimate posterior cruciate ligament strain during knee hyperextension.

Transplantation, not dialysis, corrects azotemia-dependent priming of the neutrophil oxidative burst

The oxidative burst of neutrophils from patients with renal failure before the initiation of dialysis is primed for an enhanced response after stimulation by phagocytosis or chemoattractants. This study shows that phagocytosis-stimulated oxidative burst activity remains primed in patients treated with both high-efficiency hemodialysis and continuous ambulatory peritoneal dialysis (CAPD), but it is normal in patients with a functioning renal transplant. Incubation of normal neutrophils or HL-60 granulocytes in azotemic plasma results in increased resting and phagocytosis-stimulated H2O2 production, which is rapidly reversible on removal of the plasma. Priming of the oxidative burst by azotemic plasma is independent of changes in opsonization and phagocytosis and does not require protein synthesis. These results suggest that azotemic plasma contains a substance or substances capable of reversibly priming oxidative burst activity in neutrophils and neutrophil-like cell lines. The Inability of high-efficiency hemodialysis and CAPD to normalize oxidative burst activity suggests that this substance is of higher molecular weight.

Blood flow rate: an important determinant of urea clearance and delivered Kt/V

Implementation of the Dialysis Outcomes Quality Initiative (DOQI) Guidelines for hemodialysis adequacy will necessitate an increase in delivered Kt/V for many patients. Before increasing Kt/V by prolonging the patient's treatment time, it is important to verify that the prescribed dialyzer urea clearance is being achieved. The principal determinant of dialyzer urea clearance is blood flow rate. Actual blood flow rates are frequently less than the nominal blood flow rate displayed by the dialysis machine, particularly at higher flow rates, leading to lower than expected urea clearances. The major reason for the reduction in blood flow rate is a low pressure in the arterial blood line proximal to the blood pump. This effect can be mitigated by the use of large bore access needles. For quality assurance purposes, actual blood flow rates should be determined by correcting nominal blood flow rates for pressure effects using empirical relationships or by using an ultrasonic flow meter. Because a poorly functioning blood access may further reduce the effective blood flow rate, blood access performance should also be monitored regularly.

Bacterial phagocytosis activates extracellular signal-regulated kinase and p38 mitogen-activated protein kinase cascades in human neutrophils

The hypothesis that bacterial phagocytosis by human polymorphonuclear neutrophils (PMNs) stimulates MAPK cascades that regulate respiratory burst activation was tested. Extracellular response kinase (ERK) and p38 kinase, but not c-Jun NH2-terminal kinase, activities were increased within 5 min of phagocytosis of plasma-opsonized Staphylococcus aureus (S-SA), reached maximum at 20-30 min, and remained elevated through 60 min. The role of Fcy receptors was examined using gamma globulin-opsonized SA (IgG-SA), whereas CR3 receptors were activated by particulate beta-glucan. IgG-SA stimulated a maximal ERK activity at 30 min, whereas p38 activity was maximal at 5 min. Beta-glucan stimulated maximal ERK activity at 5 min and maximal p38 activity at 2 min. Non-opsonized bacteria were ingested at 10% of the level of S-SA and stimulated a minimal increase in ERK and p38 activity at 60 min. S-SA stimulation of ERK was inhibited by wortmannin, LY294002, and genistein, but not calphostin C; whereas p38 stimulation was inhibited by calphostin C and genistein, but not wortmannin and LY294002. Simultaneous measurement of phagocytosis and H2O2 production by flow cytometry was used to assess the role of ERKs and p38 kinase in phagocytosis. The MEK inhibitor PD098059 had no significant effect on phagocytosis or H2O2 production. The p38 kinase inhibitor SB203580 significantly attenuated H2O2 production, whereas phagocytosis was unaffected. In conclusion, bacterial phagocytosis stimulates ERK and p38 activation by distinct signal transduction pathways. Phagocytosis-stimulated p38 kinase activity is necessary for optimal H2O2 production.

Activation of mitogen-activated protein kinase cascades during priming of human neutrophils by TNF-alpha and GM-CSF

The signal transduction pathways activated by tumor necrosis factor alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF) that lead to priming of polymorphonuclear leukocytes (PMNs) are unknown. The hypotheses that these cytokines stimulate multiple mitogen-activated protein kinase (MAPK) cascades, including extracellular signal-regulated kinases (ERKs), c-Jun amino-terminal kinases (JNKs), and p38 MAPK, and that these MAPKs participate in priming of human PMNs were examined. TNF-alpha stimulated a dose-dependent increase in ERK and p38 MAPK activities that was maximal at 10 min. JNKs were not stimulated by TNF-alpha or GM-CSF. GM-CSF stimulated ERK activity comparable to that of TNF-alpha, but GM-CSF was a less potent stimulus of p38 MAPK activity. The tyrosine kinase inhibitor, genistein, inhibited ERK and p38 MAPK stimulation by both cytokines. The phosphatidylinositol 3-kinase inhibitor, wortmannin, attenuated stimulation of ERKs and p38 MAPK by GM-CSF, but not TNF-alpha. GM-CSF, but not TNF-alpha, stimulated wortmannin-sensitive activation of Raf-1. TNF-alpha and GM-CSF priming of superoxide release stimulated by N-formyl-methionyl-leucyl-phenylalanine was significantly attenuated by the MEK inhibitor, PD098059, and the p38 MAPK inhibitor, SB203580. Incubation with both MAPK inhibitors produced an additive effect. Our data suggest that TNF-alpha and GM-CSF activate ERKs and p38 MAPK by different signal transduction pathways. Both ERK and p38 MAPK cascades contribute to the ability of TNF-alpha and GM-CSF to prime the respiratory burst response in human PMNs.

Prediction of anticoagulation during hemodialysis by population kinetics and an artificial neural network

All systems currently used for routine hemodialysis require heparin administration to prevent blood clotting in the extracorporeal circuit. We tested the hypothesis that population-based statistical techniques can be used to predict heparin concentrations during routine hemodialysis. Two predictive models were developed, one based on nonlinear mixed effects modeling (NONMEM) and the other on a multilayer perceptron neural network. Serial clotting time data were obtained from forty-nine patients and used to develop the models. The models were used to predict the clotting times of 70 patients in a prospective test. We determined that the neural network provided greater precision, had fewer outliers in its predictions, and did not have the model misspecification in bolus administration that the NONMEM predictions demonstrated. A final NONMEM model was developed using all data from 119 patients to identify important covariates for predicting the heparin pharmacodynamic parameters, volume of distribution, and clearance. Both the volume of distribution and clearance increased following the initiation of dialysis and as the patient's baseline clotting time increased. The volume of distribution also increased as the patient's weight increased but was decreased by smoking and diabetes. Population-based statistical techniques may provide a useful alternative to existing methods for prescribing heparin.

Quality of life during and between hemodialysis treatments: role of L-carnitine supplementation

End-stage renal disease affects every aspect of a patient's life, including perception of health and quality of life. It is likely that a hemodialysis patient's perceptions of health-related quality of life directly influence compliance with medical, nursing, and nutritional prescriptions. Because L-carnitine supplementation is known to enhance muscle strength and energy in hemodialysis patients, we hypothesized that L-carnitine supplementation would enhance a hemodialysis patient's perception of health-related quality of life. To test this hypothesis, 1 g L-carnitine or placebo was administered orally to 101 patients immediately before and after every hemodialysis treatment for 6 months. To assess health-related quality of life from the patient's perspective, the Medical Outcomes Study Short Form 36 instrument was administered before the study and at 1.5-month intervals for the duration of the study. In addition, a 10-item questionnaire designed to assess common intradialytic symptoms was administered at the end of each dialysis treatment. Other parameters analyzed included Kt/V(urea) and level of nutrition. In the 6-month group, oral L-carnitine supplementation had an early positive effect on general health (P < 0.02) and physical function (P < 0.03), but the perceived effect was not sustained throughout the 6 months of the study. In the 3-month group, L-carnitine supplementation improved vitality (P < 0.02) and general health (P < 0.01). There was no association between Kt/V(urea) and perceived health-related quality of life. Serum albumin concentration was directly correlated to how patients perceived the quality of their lives.

Natural habitats of Aedes Aegypti in the Caribbean--a review

Natural breeding habitats of Aedes aegypti in the Caribbean region were reviewed by conducting larval surveys in Trinidad. Puerto Rico, and the U.S. Virgin Islands and referring to records from the Mosquitoes of Middle America project. Twelve types of natural habitats were recorded: rock holes (9.7%), calabashes (2.4%), tree holes (19.5%), leaf axils (4.8%), bamboo joints (14.9%), papaya stumps (7.3%), coconut shells (4.8%), bromeliads (7.3%), ground pools (14.9%), coral rock holes (9.7%), crab holes (2.4%), and conch shells (7.3%), of which the coconut shell and calabash habitats were new to the Caribbean. The countries having the highest prevalence of natural habitats were Trinidad. Puerto Rico, and Jamaica, with 9 types (22.0%), 7 types (17.0%), and 6 types (14.6%), respectively. The distribution of natural habitats of Ae. aegypti in the Caribbean region is discussed in relation to vector control measures.

Maintaining blood compartment volume in dialyzers reprocessed with peracetic acid maintains Kt/V but not beta2-microglobulin removal

A dialyzer is reused if its blood compartment volume is 80% of its initial value, a condition believed to ensure that the urea clearance remains at 90% of its initial value. This criterion was developed for dialyzers containing low permeability cellulose membranes reprocessed with formaldehyde. We tested the hypothesis that the criterion is also valid for more permeable membranes when dialyzers are reprocessed with peracetic acid/hydrogen peroxide. Kt/V for urea and reduction in beta2-microglobulin concentration were measured for up to 15 uses in dialyzers containing polysulfone or cellulose membranes. Kt/V for urea did not change for either dialyzer provided blood compartment volumes remained 80% of their initial value. The reduction in plasma beta2-microglobulin concentration from predialysis to postdialysis was 30% for the first use of the dialyzer containing polysulfone membranes, but decreased significantly (P = 0.042) following reuse to 12% for the tenth use. For the dialyzers containing cellulose membranes, the reduction in plasma beta2-microglobulin concentration was 18% for the first use and decreased to 12% by the twelfth use; however, this change was not significant. We conclude that removal of urea is maintained during reuse with peracetic acid/hydrogen peroxide provided the blood compartment volume remains 80% of its initial value. However, removal of beta2-microglobulin may not be maintained, even though blood compartment volumes remain at 80% of their initial value.

A comparison of dialysers with low-flux membranes: significant differences in spite of many similarities

The solute removal characteristics and haemocompatibility of low-flux dialysers containing Cuprophan, cellulose acetate, polymethylmethacrylate (PMMA), and polycarbonate-polyether (Gambrane) membranes were compared in a multicentre cross-over clinical trial. While all four dialysers provided comparable removal of urea and creatinine, the dialyser containing PMMA membrane showed a reduced ability to remove phosphate compared to that containing Cuprophan membrane. Significant beta 2-microglobulin removal was obtained with the dialyser containing Gambrane membrane, whereas the other three dialysers had no impact on plasma beta 2-microglobulin concentrations. The ability to activate complement, measured as changes in the plasma concentrations of C3a des Arg and the terminal complement complex, and to produce leukopenia was greater for the dialyser containing Cuprophan membrane than for the other three. The ability to activate complement and cause leukopenia was not consistent among the remaining three dialysers and the degree of leukopenia could not be predicted from the level of complement activation. Neutrophil degranulation, as indicated by the release of elastase-alpha 1-proteinase inhibitor, occurred to a greater extent with the dialysers containing Cuprophan and Gambrane membranes. None of the dialysers was overtly thrombogenic as judged by changes in platelet count and plasma concentrations of the thrombin-antithrombin III complex. Our results demonstrate that although there are many similarities between dialysers containing low-flux membranes, there are also significant differences. These differences may enable improvements in therapy, while allowing continued use of low-flux dialysers.

Azotemia, TNF alpha, and LPS prime the human neutrophil oxidative burst by distinct mechanisms

The oxidative burst of neutrophils from azotemic patients (AzoPMNs) is primed for an enhanced response compared to neutrophils from normal subjects (NorPMNs). The mechanism for this priming is unknown, although TNF alpha does not further prime AzoPMNs. The present study examines the hypothesis that azotemia and TNF alpha prime neutrophils by the same mechanism. Formyl peptide receptor expression and degranulation were not primed in AzoPMNs, but were primed by both LPS and TNF alpha. LPS was also able to prime the AzoPMN oxidative burst. Guanine nucleotide exchange by multiple guanine nucleotide binding proteins, including heterotrimeric G-proteins and low molecular weight GTP-binding proteins (LMWGs), was increased in AzoPMNs, as demonstrated by GTP gamma S binding and azidoanilide GTP photoaffinity labeling. The plasma membrane density of G-protein alpha i2, alpha i3, and alpha s subunits and the density in the cytosol of the LMWG, Rap1A, was present in significantly greater amounts on plasma membranes from AzoPMNs. FMet-Leu-Phe-stimulated phospholipase D activity, but not basal activity, was significantly greater in AzoPMNs. Finally, incubation of NorPMNs in plasma from azotemic patients resulted in a significant increase in basal GTP gamma S binding. These results demonstrate that priming of AzoPMNs is restricted to oxidative burst activity and that it occurs by a mechanism distinct from that utilized by TNF alpha and LPS. While the exact mechanism remains unknown, it appears to involve a plasma factor and changes in LMWG expression or activity.

Heparinization for routine hemodialysis

Routine hemodialysis requires anticoagulation with heparin to prevent clotting in the extracorporeal circuit. Activated whole blood clotting times are used to measure the level of anticoagulation during dialysis. The magnitude of the clotting time obtained for a given level of heparin depends on the test used, and each dialysis unit must establish its own target range. The preferred dosage regimen for heparin is an initial loading dose, followed by a constant infusion. Dosage regimens based on intermittent boluses of heparin are associated with periods of under- and over-anticoagulation and require more staff attention during dialysis. Because patient responses to heparin differ markedly, the doses required to achieve suitable anticoagulation must be determined on an individual basis. The doses of heparin for an individual patient are best determined using a simple pharmacodynamic model, although they can be found empirically through trial and error. In spite of careful anticoagulation, an unsatisfactory outcome may still result. Patient-specific factors may be responsible for some of these adverse outcomes; however, in most cases they result from poor technique, including failure to deliver the prescribed dose of heparin, turbulence and foam formation in the extracorporeal circuit, and excessive access recirculation.

Hemodialysis with cellulose membranes primes the neutrophil oxidative burst

Hemodialysis with cellulose membranes causes a complement-mediated neutropenia. Changes in neutrophil function have also been reported; however, it is unclear if these changes indicate a direct effect of the membrane on neutrophils or if they are a consequence of the neutropenia. We tested the hypothesis that neutrophil oxidative burst activity is enhanced during dialysis with cellulose membranes. Resting and Staphylococcus aureus-stimulated H2O2 production were determined predialysis and in blood entering and leaving the dialyzer during the first 30 min of dialysis and in blood leaving the membrane module in a single-pass on-line model of hemodialysis. Resting H2O2 production increased slightly but significantly during the first 30 min of dialysis. Transit of neutrophils through the dialyzer caused a marked increase in stimulated H2O2 production, indicating priming of the oxidative burst. However, priming was limited to the first 5 min of dialysis before the onset of neutropenia. In contrast, stimulation and priming of H2O2 production persisted throughout 30 min of single-pass on-line perfusion. These results indicate that cellulose membranes both stimulate and prime neutrophil oxidative burst activity but that these effects are partially obscured by neutropenia.

Depletion of total salivary gland protein in blood-fed Anopheles mosquitoes

Reduction in total salivary gland protein from four anopheline vectors of human malaria, Anopheles stephensi Liston, An. albimanus Wiedmann, An. gambiae Giles, and An. freeborni Aitken, was quantified after mosquitoes blood-fed to repletion on human volunteers, hamsters or through a Baudruche artificial membrane. Total salivary gland protein from pools of six unfed mosquitoes ranged from 4.33 to 7.91 micrograms/ml. The difference between the total protein of glands from unfed and blood-fed mosquitoes for all species ranged from 1.77 to 3.12 (micrograms/ml for six pooled salivary glands. Total salivary gland protein for mosquitoes blood-fed to repletion was significantly less than that of unfed controls from the same cohort. Reduction in total salivary gland protein for An. freeborni and An stephensi blood fed to repletion on human volunteers, hamsters, and a Baudruche membrane ranged from 24 to 46%, from 43 to 56%, and from 24 to 51%, respectively. An. stephensi mosquitoes were allowed to blood feed on humans for 0 (unfed), 0.5-, 1.0-, 2.0-min time periods or to repletion (> 2-5 min). As feeding time increased, there was a significant decrease in total amount of protein in the salivary glands. This decrease was proportional over time, indicating that salivation occurred continuously from the beginning (probing) of blood feeding to withdrawal of the mosquito mouthparts at repletion. These data indicate that during blood feeding there difference between species in the salivary gland output measured as amount of protein depleted from the salivary glands and that depletion of salivary protein from the glands occurred continuously as mosquitoes fed to repletion.

Chemoattractant receptor-specific differences in G protein activation rates regulate effector enzyme and functional responses

The hypothesis that disparate neutrophil functional responses to various chemoattractants are regulated by receptor-specific rates of G protein activation was examined in HL-60 granulocytes. The initial rates of G protein activation and the affinity of receptor-stimulated G proteins for GTP gamma S in HL-60 membranes stimulated by fMet-Leu-Phe, C5a, and leukotriene B4 (LTB4) differed significantly among the chemoattractants, with a rank order of fMet-Leu-Phe > C5a > LTB4. Equilibrium GTP gamma S binding showed that all three chemoattractants activated a common pool of G proteins. Stimulation of phospholipase D activation, measured as phosphatidylethanol generation, and superoxide release in intact cells also occurred with a rank order of fMet-Leu-Phe > C5a > LTB4. On the other hand, the rank order of receptor affinities for ligand and of the EC50 of chemoattractant stimulation of GTP gamma S binding was C5a > LTB4 > fMet-Leu-Phe. C5a and LTB4 receptor densities were similar but were less than formyl peptide receptor density. Graded pertussis toxin treatment proportionally reduced superoxide release and phospholipase D activation to all three chemoattractants. The results suggest that receptor-specific differences in G protein affinity for guanine nucleotides lead to different rates of guanine nucleotide exchange and, thereby, contribute to disparate effector enzyme and functional responses.

Polymorphonuclear leukocyte oxidative burst is enhanced in patients with chronic renal insufficiency

Previous reports that polymorphonuclear leukocyte (PMN) function is impaired in hemodialysis patients do not differentiate between effects of dialysis and of uremia. The hypothesis that chronic renal insufficiency impairs PMN function was tested. Phagocytosis and oxidative burst were measured in PMN from patients with varying degrees of chronic renal insufficiency impairs PMN function was tested. Phagocytosis and oxidative burst were measured in PMN from patients with varying degrees of chronic renal insufficiency (creatinine clearance, 6 to 35 mL/min per 1.73 m2) and normal subjects. The ability of tumor necrosis factor-alpha (TNF-alpha) to prime the oxidative burst was also assessed. Phagocytosis of Staphylococcus aureus and basal H2O2 and O2- release by PMN did not differ between normal subjects and patients with chronic renal insufficiency. However, the oxidative burst stimulated by S. aureus and formyl-Met-Leu-Phe, but not phorbol myristate acetate, was significantly enhanced in PMN from patients with chronic renal insufficiency. The increase in formyl-Met-Leu-Phe-stimulated oxidative burst correlated significantly with the level of renal function. TNF-alpha significantly increased S. aureus-induced H2O2 production in normal PMN, but not in PMN from patients with chronic renal insufficiency. These data indicate that chronic renal insufficiency does not impair PMN phagocytosis and oxidative burst. To the contrary, it enhances receptor-mediated oxidative burst. The inability of TNF-alpha to further enhance the oxidative burst suggests that PMN exist in a primed state in patients with chronic renal insufficiency.

Technical challenges to successful dialyzer reuse

Limitations of dialyzer reuse technology may contribute to adverse patient outcomes. Assessing changes in dialyzer performance by measuring changes in total cell volume may not be valid for all membranes and reprocessing methods. Systems which determine dialyzer performance on-line are superior. Compliance with standards for microbial contamination of reprocessing fluids is poor and improvements in water treatment system design and monitoring are needed. Technological innovation is required to enable dialyzer performance to be monitored over an expanded molecular weight range and to ensure that dialyzer reprocessing can be routinely performed with sterile, non-pyrogenic solutions.

The effects of RU 33965 and RU 34030, two new 3-cyclopropyl carbonyl imidazobenzodiazepines, on GABAA receptor-mediated synaptic transmission in cerebellar slices in the rat

1. Two 3-cyclopropyl carbonyl imidazobenzodiazepines, RU 33965 and RU 34030, were tested for their ability to modulate GABAA synaptic transmission in rat cerebellar slices. The action of the full benzodiazepine agonist RU 32007 and the inverse agonist Ro19-4603 were tested for comparison. 2. Extracellular recordings were made from the Purkinje cell layer of the cerebellar slices and inhibition induced by just threshold electrical stimulation of the parallel fibres was bicuculline sensitive. 3. The major effect of RU 32007 when examined at 100 nM and 1 microM was to increase the GABAA mediated inhibition in the slice. 4. In contrast the major effect of the inverse agonist Ro19-4603 was to reduce the period of inhibition. 5. RU 33965 and RU 34030 at 10 and 1 microM respectively either had little effect on GABAA mediated inhibition or decreased it slightly. 6. RU 34030, 1 microM, abolished the agonist effect of RU 32007, 1 microM. 7. The effects of RU 32007 and Ro19-4603 were abolished by the benzodiazepine antagonist flumazenil. 8. It is concluded that both RU 33965 and RU 34030 have marginal inverse agonist properties.

Soluble tumor necrosis factor receptors are increased in hemodialysis patients

Tumor necrosis factor-alpha (TNF alpha) interacts with cells through specific membrane receptors. Exposure to agonists, such as C5a, causes cells to shed these receptors, forming soluble TNF alpha binding proteins (sTNFR). Because cellulose membranes activate complement, we tested the hypothesis that dialysis with these membranes contributes to the increased levels of sTNFR observed in hemodialysis patients. sTNFR levels were measured pre- and post-dialysis in patients treated with dialyzers containing new cellulose membranes. Plasma sTNFR concentrations were markedly increased pre-dialysis, compared with normal (38.3 +/- 13.5 ng/ml versus 2.1 +/- 0.7 ng/ml), and increased further during dialysis, even after post-dialysis concentrations were corrected for hemoconcentration. We examined the impact of the increased sTNFR levels on the ability of TNF alpha to prime neutrophil superoxide production in cross-incubation experiments. When normal neutrophils were incubated with TNF alpha in the presence of hemodialysis patient plasma, the resulting increase in fMLP stimulated superoxide production was significantly less than when normal plasma was used. Incubation of hemodialysis patient neutrophils in normal plasma only partly restored their ability to be primed by TNF alpha, suggesting an intrinsic functional defect in these cells, in addition to the effects of sTNFR. Our results suggest that dialysis with cellulose membranes contributes to the increased levels of sTNFR observed in dialysis patients, and that these concentrations are sufficient to impair the normal actions of TNF alpha.

Biocompatibility of a new high-permeability modified cellulose membrane for haemodialysis

The biocompatibility and solute permeability characteristics of a high-permeability modified cellulose membrane (Hemophan-HP) (He-HP) were compared with those of two synthetic membranes (poly(ethylene-co-vinyl alcohol) (EVAL) and poly(acrylonitrile-co-sodium methallyl sulphonate) (AN69)) and Cuprophan in a multicentre, four-way cross-over clinical trial. Cuprophan membranes caused significant complement activation, leukopenia, and granulocyte elastase release. He-HP membranes demonstrated a lesser effect, which was similar to that observed for the EVAL membrane, although less than that seen with the AN69 membrane. A similar order for the four membranes was seen for their effect on platelets. Cuprophan membranes provided superior small-molecule removal to the other three membranes. In contrast, Cuprophan was essentially impermeable to beta 2-microglobulin, whereas He-HP, EVAL, and AN69 allowed the removal of 60-90 mg of beta 2-microglobulin per treatment. However, a decrease in the plasma concentration of beta 2-microglobulin was observed only with the AN69 membrane, most probably as a result of the ability of that membrane to adsorb proteins. Our results demonstrate that high-permeability membranes of comparable biocompatibility to some synthetic membranes can be fabricated from cellulose derivatives.

Effects of RU33368, a low affinity ligand for neuronal benzodiazepine receptors, on rodent behaviours and GABA-mediated synaptic transmission in rat cerebellar slices

1. The effects of the low affinity benzodiazepine receptor ligand RU33368 were studied on rodent behaviours and on GABA-mediated synaptic transmission in rat cerebellar slices. 2. RU33368 inhibited stress induced ultrasounds in rat pups without inducing marked muscle relaxation. RU33368 also enhanced operant responding in rats that had been suppressed by mild footshock. These effects of RU33368 in these two models of anxiety were both blocked by the benzodiazepine antagonist Ro15-1788 (flumazonil). 3. In cerebellar slices RU33368 enhanced stimulus-induced synaptic inhibition of Purkinje layer cells with a minimal effective concentration in the order of 1 microM. The classical benzodiazepine agonist RU32007 was approx. 10 times more potent. This action of RU33368 was blocked by Ro15-1788. 4. The minimal effective concentration of RU33368 fully blocked the effect of RU32007 in 2 of 4 cells tested and partially antagonized it in a third cell. 5. These data suggest that RU33368 is a partial agonist at benzodiazepine receptors and this, at least in part, explains its non-sedative anxiolytic behavioural profile.

Origin and fate of fetuin-containing neurons in the developing neocortex of the fetal sheep

The development of the neocortex has previously been extensively studied in carnivores (cat and ferret), rodents (rat and mouse) and primates (monkey and human). In these species, it has been shown that the initial population of cells migrating from the ventricular zone forms the primordial plexiform layer. This is subsequently split into marginal zone and subplate zone by the insertion of later-migrating cells into the primordial plexiform layer, to form the cortical plate proper. Many of the cells derived from the split primordial plexiform layer are transient. The neurons of the subplate zone are found in the deeper part of layer VI, and white matter deep to layer VI in the more mature cortex; most of these neurons disappear by adulthood. [3H]-thymidine labelling in the present study has shown a similar pattern of neocortical development in Artiodactyla (sheep). In addition it has been shown that the previously described staining of subplate and cortical plate cells for the fetal protein fetuin indicates that fetuin is a useful marker for a proportion of this transient population of neurons and defines its extent in neocortical development more clearly. Dividing cells were labelled by a single intra-amniotic injection of [3H]-thymidine at E26 to E35 (birth is at E150). The brains were subsequently examined at E40 or E80 for [3H]-thymidine labelling and fetuin staining by a combination of autoradiography and immunocytochemistry. The earliest generated neocortical cells detected in this study (E26) were found in two layers by E40, the outer marginal zone and inner subplate zone. Neurons of the marginal zone were generated up to E28; those of the early subplate zone were generated up to E31. The cortical plate proper was generated by cells "born" on E32 and later. This sequence is similar to that described in other species, especially the cat. A proportion of the early-generated neurons in the marginal zone, subplate zone and early cortical plate stained for fetuin. By E80 these earliest-generated, fetuin-positive cells were found in the white matter deep to the forming neocortical layers and in layer VI. In adult brains no fetuin-positive neurons could be identified in the neocortex, and neurons had almost entirely disappeared from the white matter. The fetal glycoprotein fetuin seems to be specifically associated with a population of cells that has the same developmental history as the transient marginal zone and subplate neurons described in other species.(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of prostaglandin F2 alpha and prostacyclin interactions in the isolated perfused rat lung

To characterize the interactions between prostaglandin F2 alpha and prostacyclin in controlling tone in the pulmonary circulation, isolated rat lungs were ventilated, perfused with blood, and subjected to challenge by prostaglandin F2 alpha in increasing doses. The pulmonary resistance was evaluated using occlusion techniques that separate the resistance into segments of large and small arteries and veins. The total vascular compliance was evaluated using outflow occlusion. Resistance increased after prostaglandin F2 alpha, and this resistance change was primarily in the small artery segment. The maximum resistance increase by prostaglandin F2 alpha (Rmax,PGF2 alpha), calculated from the Michaelis-Menton equation, was 16.6 +/- 3.6 cmH2O.l-1.min.100 g-1 for total vascular resistance with a concentration required to produce 50% Rmax (K0.5) of 5.26 +/- 3.57 nM. The Rmax,PGF2 alpha for small artery resistance was 13.5 +/- 2.4 cmH2O.l-1.min.100 g-1 with a K0.5 of 2.35 +/- 1.57 nM. The vascular compliance decreased during vasoconstriction by prostaglandin F2 alpha, and the maximum decrease in compliance (Cmin,PGF2 alpha) was -0.43 +/- 0.12 ml/cmH2O with a K0.5 of 2.84 +/- 2.99 nM. At each dose of prostaglandin F2 alpha, prostacyclin was administered in increasing doses to reverse the vasoconstriction caused by prostaglandin F2 alpha. For each concentration of prostaglandin F2 alpha, prostacyclin almost completely reversed the resistance increases and approximately one-half the compliance decrease. The maximum change in vascular resistance or compliance produced by prostacyclin was dependent on the dose of prostaglandin F2 alpha; yet the K0.5 for prostacyclin was within the picomolar range for all doses of prostaglandin F2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)